During the past year, we have used the resources at CHESS to extend the resolution and improve the quality of diffraction data for crystalline complexes involved in signal transduction, transcriptional and translational regulation. Complete native and/or derivative data sets collected at CHESS are being used to solve the crystal structures of: 1) the DNA binding domain of human nerve growth factor induced-B bound to a DNA response element at 2.0 _, and 2) the human estrogen receptor ligand binding domain. Furthermore, data collected at CHESS have been instrumental in solving the atomic resolution structures of: 1) the TATA-binding protein from Pyrococcus woesii alone and in a ternary complex with the P. woessi transcription factor TFIIB and DNA, 2) the elongation factor Ts from Thermus thermophilus, 3) a complex of the translational elongation factors Tu and Ts from Thermus thermophilus, and 4) the ligand binding/oligomerization domain of the bacterial arginine receptor.